1. Field of the Invention
This invention relates to an electronically controlled sample warper capable of preparing warping yarns in orderly layered condition without regard to the warping length, thereby enabling warping of long samples or products manufactured in small lots.
2. Description of the Related Art
Conventional electronically controlled sample warpers are exemplified by Japanese Patent Laid-open Publication No. 62-62942, which generally comprises: driving and driven shafts projecting centrally from opposite ends of a hollow shaft cantilevered at the driving-shaft side; a first small gear loosely mounted on the driving shaft and fixed to a pulley; a second small gear loosely mounted on the driven shaft and fixed to a yarn introduction lever; third and fourth small gears mounted on opposite ends of an auxiliary shaft extending through the hollow shaft and meshing the first and second small gears respectively, to cooperate with each other; drum frames mounted on the driven-shaft side of the hollow shaft and each having an outer periphery having alternately an arcuate portion and a straight portion; a pair of rollers disposed one on the arcuate portion of each of the drum frames; and a warper drum loosely mounted on the hollow shaft and having horizontal drum spokes carrying the rollers around which conveyor belts are wound. The conveyor belts are simultaneously driven to a common amount of fine movement by a drive member threadedly engaged with interior screw shafts of planetary gears meshing with a sun gear suitably driven from the exterior; as the sun gear rotates, the planetary gears rotate concurrently. The distal end of the yarn introduction lever is bent inwardly to provide a yarn introducing part disposed adjacent to the front end of the outer periphery of the warper drum. The warper also includes: a shedding means for forming a shed and a cut shed by selecting warp yarns (to be wound on the warper drum) over and under shedding bars and cut shedding bars; a total yarns counter count means for rendering an up signal, of a total counter for counting the total number of the warp yarns, to be on or off; a total yarns completion termination means for terminating the operation of the warper when the total number of the warp yarns reaches a predetermined value; a conveyor belt leftward moving means for moving the conveyor belt leftwardly; and conveyor belt rightward moving means for moving the conveyor belt rightwardly; an operation/termination means for transmitting the rotation of a main motor to the yarn introduction lever; a yarn selection means for controlling a yarn selection guide and a yarn removing unit; a yarn pressing solenoid means for rendering a solenoid of a yarn relaxation preventing (yarn pressing) unit operative and inoperative; and a windings count means for counting the number of windings of the yarns and for displaying the counted result. By selecting the kind of yarns 0-n, and setting the number of yarn, the number of repeats, the number of windings, the quantity of movement of the conveyor belt, a desired pattern of warping can be achieved automatically.
However, in this conventional warper, since an ordinary motor is used as the main motor, it is impossible to vary the rate of rotations during operating so that miscatches and mischanges as well as yarn breakage are inevitable when exchanging yarns. Additionally it is impossible to terminate relaxing and to perform jogging, thus causing only inadequate operating efficiency. For setting the density of warp yarns, the rate of moving the conveyor belt is determined by varying the gear ratio of speed change gears operatively connected to the main motor. Since the conveyor belt is moving even during idling of the remainder of the machine, regular windings of yarn on the warper drum are difficult to achieve so that the tension and the warping length would finally vary during the winding operation.
In order to overcome the above-mentioned problems, proposals have been made to employ an inverter motor or an AC servo motor in the warper (Japanese Patent Publications Nos. 64-10609 and 64-10610).
In a warper provided in accordance with another prior proposal, a plurality of warp yarns can be concurrently wound on a warper drum with omitting a yarn exchanging step to eliminate any time loss for the yarn exchange, thus reducing the warping period of time (Japanese Patent Publication No. 4-57776).
In the conventional electronically controlled sample warpers described above, in synchronism with rotation of the yarn introduction lever to wind the yarn at a fixed position around the warper drum by the necessary number of turns or windings (number of warp yarns.times.warping length), the conveyor belts on the warper drum are moved in the warping direction to determine the warping width. In this instance, the amount of feed or movement of the conveyor belts per each revolution of the yarn introduction lever is determined by (warping width/number of warp yarns).times.(warping length/circumference of warper drum). Accordingly, if the warping length is relatively small such, for example, as equal to the circumference of the warper drum, the amount of feed of the conveyor belts per each revolution of the yarn introduction lever will be larger than the diameter (thickness) of the yarn. The yarn can, therefore, be neatly wound on the warper drum with individual turns arranged regularly, as shown in FIG. 38 of the accompanying drawings. After warping, the yarn can be smoothly rewound on a beam of a weaving machine in the form of a sheet.
However, when the warping length is relatively large such, for example, as nine times the circumference of the warper drum, the amount of feed of the conveyor belts per each revolution of the yarn introduction lever 6 is considerably smaller than the diameter (thickness) of the yarn. This means that the yarn is inevitably wound on the previously wound layer or winding of the yarn. In this instance, however, since the yarn is wound on the warper drum without restriction and hence it has an unrestrictedly wound structure such as shown in FIG. 39. Accordingly, when the windings of yarn are rewound on beams on the weaving machine in the form of sheets and in the reverse order of warping, i.e., 9 - 7 - 6 - 4 - 3 - 2 - 1, the yarn is likely to be entangled and, hence, cannot be drawn out from the warper drum A.
In other words, in the case of single winding (warping length=circumference of warper drum), the conveyor belts move a distance equal to the warp density (warp yarn pitch) per each revolution of the yarn introduction lever. On the other hand, in the case of multi-winding, such as ninth winding (warping length=warper-drum's circumference .times.9), the conveyor belts move only a distance equal to [warp density (warp yarn pitch)/9] per each revolution of the yarn introduction lever. As a result, the yarn is layered at random, as shown in FIG. 39.
Thus, depending on various conditions such as fabric density, yarn diameter or thickness and warping length, smooth rewinding of the yarn cannot be achieved if four or more layers or windings of yarn are wound on the warper drum. Accordingly, there is a keen demand for an electronically controlled sample warper which is capable of warping yarns on the warper drum, with windings of yarns neatly layered in regular order: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 (nine windings).